edison



2 Sheets-Sheet 1.

(.No Model.)

T. A; EDISON.

DUPLJEX TELEGRAPHY.

' Patented Dec. 29, 1885.

(No Model.) 2 Sheets-Sheet 2.

' T. A; EDISON.

DUPLEX TELEGRAPHY.

No. 333,290. Patented Dec. 29, 1885.

UNITED STATES ATENT OFFICE.

THOMAS A. EDISON, OFMENLO PARK, NEWV JERSEY.

DUPLEX TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 333,290, dated December 29, 1885,

Application filed May 8, 1885. Serial No. 164,557.

To all whom it may concern.-

Be it known that I, THoMAs A. EDISON, of Menlo Park, in the county of Middlesex and State of New Jersey, have invented a new and useful Improvement in Telegraphy, (Case No. 649,) of which the following is aspecification.

The object I have in view is to increase the capacity of telegraphlines in a simple and practical manner by the production of instru ments and connections permitting the transmission of two sets of Morse signals back and forth over the line at the same time without interfering one with the other, and not only between terminal offices, but between a terminal office and any intermediate office, or between intermediate offices alone.

The invention is especially applicable to local lines, or to lines having several offices won them, to which it can be applied at small expense, each office upon the line being provided with instruments for transmitting and receiving a second set of signals, and with devices for making the two sets of signals independent and for insuring against their interference. Not only is the capacity of the telegraph-lines doubled, but the delays occasioned on lines with several offices by the interfering of two or more operators in their attempts to gain possession of the line are diminished.

The general objects before stated are fully accomplished by apparatus described and claimed in my application No. 648.

The present invention is an improvement upon that apparatus, and relates more particularly to' a peculiar transmitter for producing the momentary and sharply-defined waves to which the diaphragm-sounder responds, and also to the manner of connecting the diaphragm-sounder to the line.

In the accompanying drawings, forming a part hereof, Figure 1 is a view in diagram of a line with four oflices; Fig. 2, a separate view in diagram of the arrangement for one office; Figs. 3, 4, and 5, views similar to Fig. 2 of modified arrangements; Fig. 6, a view of a further modification of the transmitter; Fig. 7, a sectional view of a dash-pot for varying alternate signals, and Fig. 8 a view of another device for the same purpose.

Like letters denote corresponding parts in all the figures.

.as shown in Fig. 1.

(No model.)

The line L L is grounded at its ends, and has the usual main battery, M B. The four offices A B O D have each the ordinary set of Morse instruments, composed of a relay, a, and key b in line, the former workinga sounder (not shown) in the circuit of a local battery. With these ordinary Morse instruments telegraphing is carried on by Morse signals in the usual Way. At each office the set of Morse instruments (the relay and key) or the key alone is shunted by a condenser, E, which keeps the line closed constantly to signals produced by momentary and sharplydefined Waves, which are received on diaphragm-sounders F, located one at each office, at which there is also located a transmitter for producing such waves. This transmitter is an instrument constructed to make and break circuit with great rapidity, so as to send for each signal a large number of such -momentary and sharply-defined waves. It

may be constructed in a variety of ways. The form I prefer is a rapidly-revolving circuitcontroller, G, kept in motion by a suitable electrical or mechanical motor. This circuitcontroller may be placed directly in line, as shown in Fig. 5; but I prefer to place it in the primary circuit of an induction-coil, H, the secondary circuit of which is directly in the line, as shown in Figs. 2, 3, and 4 or is in a condenser-circuit connected with the line, This condenser-circuit may be a ground-connection from line or a shunt around a resistance or magnet in line.

In the primary circuit of H is a battery, 0, and in a shunt around the revolving circuitcontroller G isasounder, I, with both its front and back points connected in circuit and operated by a key and local battery, as shown in Figs. 1 and 2.

In place of a sounder, a key, 1, Figs. 3, 4, and 5, may be employed, connected to close circuit at front and back points. Normally, the sounder or key closes this shunt at its back contact, and the revolution of the circuit-controller does not affect the inductioncoil. The movement of the sounder-lever (or the key) first breaks this shunt at its back point and thenv closes it at its front point. During this interval, while the shunt-circuit is open the circuit-controller produces aseries of waves in the primary of the induction-coil,

and the secondary of such coil throws upon the line a large number of momentary and sharply-defined waves. The return movement of the sounder-lever or the key first opens and then closes the shunt-circuit, producing the same result as in the forward movement. The momentary and sharply-defined waves do not work the relays, but are respondedto by the diaphragm sounders, and are translated by them into sound,t-he intervals between the signals representing dots and dashes. The number of waves transmitted for each signal is sutficiently great to make a corresponding number of air-waves audible, and hence the sound is transmitted electrically instead of being produced by a mechanical blow, which is the result of a single electrical impulse, as at an ordinary Morse sounder.

To make the signal different for the down and up stroke of key, I connect the lever of sounder I with a dash'pot, J, the plunger of which has a valve, opening in one direction, Fig. 7, so that the sounder-lever will have a quicker movement in one direction than the other. This movement is preferably made quicker on the upstroke of key, causing the second signal marking the interval de noting a dot or dash to be weaker or shorter or of different tone from the firstsignal. This prevents confusion in receiving.

Instead of a dash-pot with valved flanges for varying alternate signals,the device shown in Fig. 8 can be used. This consists of a retarding-tan, e, secured to a spindle with ratchetwheel, f. The cog-wheel g, loose on the same spindle, has a pawl, 72, which engages with ratchet-wheel f. The soundenlever has on its end a toothed sector, 1', engaging with wheel g. The movement of the sounder-lever in one direction will turn the fan. In the other direction, the wheel 9 turns free of the ratchet-wheelf.

My transmitter may be constructed as shown in Fig. 6. A magnet, K, worked by a key and local battery, operates a lever, k, which is extended the required distance to get the necessary movement. At its end it carries a finger, 1, playing over the surface of a contact block, L. This contact-block has its face composed of a large number (preferably fifty or more) of thin plates separated by insulation. This block L and the lever in are connected in circuit, preferably in the primary of inductioncoil H, and the movement ofk causes the circuit to be made and broken rapidly, th rowing upon the line momentary and sharply-defined waves. A dash-pot or the fan-regulator is attached to lever is to vary alternate signals.

The diaphragmsounders F may be any form of telephone-receiver.

I prefer to use my electro-motograph receiver, although a magnetoelectric or other telephone receiver can be employed.

The diaphragm'sounders may be located directly in line, Figs. etand 5, or in condensercircuits connected with line, Figs. 1 and 3; but I prefer the arrangement shown in Fig. 2, wherein the diaphragm-sounder is located in the tertiary circuit of induction-coil H, and is operated by induction from the line.

What I claim is- 1. In a system of Morse telegraphy, the combination, with ordinary Morse telegraph-instruments shunted. to keep the line constantly closed to momentary and sharply-defined waves, of diaphragm-sounders and transmitters transmitting Morse signals electrically by throwing upon the line for each signal a large number of momentary and sharply defined waves, which do not work the Morse relays, but are responded to by the diaphragm-sounders, substantially as set forth.

2. In a system of Morse telegraphy, the combination,with a diaphragm-sounder,of atrans mitter consisting of a circuit-breaker and a controlling-key, the former being constructed to make and break circuit rapidly a large number of times for each movement of the controllingkey, substantially as set forth.

3. In a system of Morse telegra phy, the combination, with adiapbragm sounder, ofa transmitter consisting of a circuit-breaker and a controllingkey, the former being constructed to make and break circuit rapidly a large nu mber of times for each movement of the controlling-key, and means for retarding the movement of the transmitter in one direction, so as to vary alternate signals, substantially as set forth.

4. In a system of Morse telegraphy, the combination,with adiaphragm-sounder, ofat-ransmitter composed of a revolving circuit-controller, and a shunt around the same controlled by a key, substantially as set forth.

5. In a system of Morse telegraphy, the combination, with a diaphragmsounder, of an induction-coil with secondary in line,and atransmitter in the primary of such coil, consisting of a circuit-breaker and a controlling-key, the former being constructed to make and break such primary circuit rapidly a large number of times for each movement of the controllingkey, substantially as set forth.

6. In a system of Morse telegraphy, the combination, with ordinary Morse telegraph-instruments shunted to keep the line constantly closed to momentary and shaplydefined waves, of a transmitter of such waves, and a diaphragm-sounder responding to such waves and connected inductively with the line, substantially as set forth.

This specification signed and witnessed this 30th day of April, 1885.

THOMAS A. EDISON.

It is hereby certified that in Letters Patent No. 333,290, granted December 29, 1885, upon the application of Thomas A. Edison, of Menlo Park, New Jersey, the title of the invention was erroneously written and printed Duplex Telegrnphy, whereas the said title should have been written and printed Telegraphy; and that the said Letters Patent should be read with this correction therein to make the swine conform to the record of the case. in the Patent Ofliee.

Signed, conntersigned, and sealed this 26th day of January, A. D. 1886.

H. L. HULDROW, Acting Secretary of the I meriow [SEAL] Oountersigned M. V. MONTGOMERY,

Commissioner of Patents. 

